HEWLETT PACKARD (HP) 166D
Service Manual

Section 111 Paragraphs 3-3 to 3-4 (1) On Model 166D, s e t SWEEP SELECTOR to MIXED SWEEP, DELAY LENGTH to about 5 CM, DELAY FUNCTION to TRIGGER MAIN SWEEP, and SWEEP MODE to FREE RUN. (2) On oscilloscope, s e t SWEEP MODE to PRESET. (3) Set DELAYING SWEEP on Model 166D to 20, 10, 5, 2, and 1 MlLLISECOND and s e t SWEEP TIME on oscilloscope so main sweep is in each case 100 times faster than delaying sweep. (4) Observe t r a c e on c r t f o r each combination of sweeps. Left half of t r a c e should be brighter than right half. An increase of t r a c e intensity at.right end of the t r a c e indicates incorrect relative sweep lengths. Refer ,to section IV of this manual and to oscilloscope manual f o r sweep length adjustments.
3 -3. O P E R A T I N G P R 0C EDU R ES

Model 166D, MX-2962/USM-l05A

c. DELAY CONTROL. T h e DELAY FUNCTION, DELAYING SWEEP, DELAY LENGTH, and SWEEP SELECTOR controls all affect the delay or the way the delay appears on the crt.
The DELAY FUNCTION switch determines whether the Model 166D triggers or arms the main sweep a t the end of the delay period. With the DELAY FUNCTION set t o TRIGGER MAIN SWEEP, the Model 166D s t a r t s the main sweep immediately after the delay period. After completing i t s cycle, the main sweep is ready f o r another starting trigger from theModel166D. With the DELAY FUNCTION set to ARM MAIN SWEEP, the Model 166D arms but does not s t a r t the main sweep a t the end of the delay period. The main sweep then requires a trigger as selected by the TRIGGER SOURCE switch of the oscilloscope. After one cycle, the main sweep remains disabled until rearmed by the Model 166D. The DELAYING SWEEP switch'determines the sweep time of the delaying sweep whether o r n o t the delaying sweep appears on the crt. T h i s sweep is the reference f o r delay measurements. The DELAY LENGTH control determines delay length measured in centimeters along the delaying sweep. Thus the delay period is the product of DELAY LENGTH and DELAYING SWEEP settings. The SWEEP SELECTOR determines the horizontal presentation on the crt. T h e r e a r e four options: (1) MAIN SWEEP. The oscilloscope operates normally: the main sweep drives the trace across the crt; and there is no delay. (2) DELAYING SWEEP. The delaying sweep drives the t r a c e across the crt. The main sweep is triggered ( o r armed) a t the end of the delay period, and the time interval of the main sweep is indicated by a brightened segment on the crt display. (3) MAIN SWEEP DELAYED. T h e main sweep drives the trace across the crt after thedelay period. T h e display on the c r t is the expansion of the brightened part of the delaying sweep display. M!XED SWEEP. The delaying sweep drives (4) the t r x e f o r the delay period, after which the main sweep starts. The trace i s then driven by the sweep which is farther along in i t s cycle. To drive the t r a c e during any part of the display, then, the main sweep must be fast enough t o pass the delayingsweep before the delaying sweep drives the trace off the right-hand side of the c r t screen. (There is a display on the crt even though the main sweep is slower than the delaying sweep, but it is not usable.) Since there is some delay beyond that indicated by the DELAY LENGTH control, total delay shoald be read from the crt.
3-4. GENERAL O P E R A T I N G NOTES.

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a. FRONT-PANEL CONTROLS. Front-panel controls and their functions are shown in figure'3-1. T h e paragraphs below expand upon the control and connector functions indicated in the figure.
b. SWEEP START CONTROL. Four front-panel controls affect the s t a r t of the delaying sweep. They include the TRIGGER SOURCE switch, TRIGGER LEVEL control, TRIGGER SLOPE switch, andSWEEP MODE control. The TRIGGER SOURCE switch selects the source of the sweep trigger: the power line (LINE), the signal applied t o the vertical amplifier of the oscilloscope (INT), or an external signal applied t o the TRlGGER SOURCE I N P U T connector (EXT AC or EXT DC). The TRIGGER LEVEL control selects the voltage level on the trigger signal a t which the sweep starts. T h e control provides continuous adjustment of the trigger level from about -30 volts t o about +30 volts on external signals and over a range equivalent to about six centimeters of v e r t i w l deflection on internal trigger signals. T h e TRIGGER SLOPE switch determines whether the delaying sweep s t a r t s on the positive-slope or negative-slope portion of the trigger signal. T h e SWEEP MODE control determines whether the d-laying sweep requires a trigger or free runs. The control i s continuously adjustable with a switched position a t its counterclockwise extreme. The switched position, PRESET, is the best overall setting for the control when the trigger signal is below about 10 mc. This position i s internally s e t f o r optimum trigger operation. F o r trigger signals above about 10 mc, free-running operation may be better. In this c a s e the trigger signal synchronizes the delaying sweep with the signal being viewed. F o r very high frequency trigger signals, a fine adjustment of theSWEEP MODE and/or TRlGGER LEVEL controls may be necessary to stabilize the presentation on the crt. 3-2

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a. DELAYED TRIGGER OUTPUT. The delayed trigger available a t the front-panel DEL. TRIG. OUTPUT connector coincides with the trigger signal 01227-1